The following abbreviations that may be found in the specification and/or the drawing figures are defined as follows:                3GPP third generation partnership project        BCCH broadcast control channel        BMSC broadcast-multicast service center        CDM code division multiplexing        CSI channel state information        D2D device-to-device        DCI downlink control information        DL downlink        CP cyclic prefix        EDGE enhanced data rates for GSM evolution        E-UTRA evolved universal terrestrial radio access        eNB, eNodeB evolved node B/base station in an E-UTRAN system        E-MBMS evolved multimedia broadcast multicast service        EPC evolved packet core        E-UTRAN evolved UTRAN (LTE)        FDM frequency division multiplexing        GERAN GSM EDGE radio access network        GSM global system for mobile communications        HARQ hybrid automatic repeat request        ID identification        LCID locale identifier        LTE long term evolution        LTE-A long term evolution advanced        MAC medium access control        M2M machine-to-machine        MBMS multimedia broadcast multicast service        MBSFN multimedia broadcast multicast service single frequency network        MCCH multicast control channel        MCE multi-cell/multicast coordination entity        MCH multicast channel        MCS modulation and coding scheme        MIB master information block        MIMO multiple input multiple output        MME mobility management entity        M-RNTI MBMS radio network temporary identifier        MSI MCH Scheduling Information        MSP MCH scheduling period        MTCH multicast traffic channel        MTC machine type communication        O&M operations and maintenance        PDCCH physical downlink control channel        PDSCH physical downlink shared channel        PDU protocol data unit        PRB physical resource block        PTM point-to-multipoint        PUCCH physical uplink control channel        PUSCH physical uplink shared channel        RAN radio access network        RNTI radio network temporary identifier        RLC-UM radio link control unacknowledged mode        RRC radio resource control        Rx reception, receiver        SGW serving gateway        SIB system information block        SR scheduling request        TDM time division multiplexing        TSG telecommunication security group        TSG-SA TGS service and system aspects        Tx transmission, transmitter        TTI transmission time interval        UE user equipment        UP uplink        UTRAN universal terrestrial radio access network        WG working group        
Device-to-device (D2D) communication may enable new service opportunities and reduce the eNB load for short range data intensive peer-to-peer communications. Qualcomm has proposed a study item for the D2D in 3GPP TSG-RAN #52 plenary, 31 May-3 Jun. 2011, e.g., see Tdoc-RP-110706, “On the need for a 3GPP study on LTE device-to-device discovery and communication”, Qualcomm Incorporated, 3GPP TSG-RAN #52, Bratislava Slovakia May 31-Jun. 3 2011; Tdoc-RP-110707, “Study on LTE Device to Device Discovery and Communication—Radio Aspects, “Qualcomm Incorporated, 3GPP TSG-RAN #52, Bratislava Slovakia May 31-Jun. 3 2011; Tdoc-RP-110708, “Study on LTE Device to Device Discovery and Communication—Service and System Aspects,” Qualcomm Incorporated, 3GPP TSG-RAN #52, Bratislava Slovakia May 31-Jun. 3 2011.
One of the main targets is to evolve the LTE platform in order to intercept the demand of proximity-based applications by studying enhancements to the LTE radio layers that allow devices to discover each other directly over the air. Then the devices may communicate directly if it makes sense from a system management point of view upon appropriate network supervision.
The document Tdoc-RP-110706 quoted above states as follows: “This radio-based discovery process needs also to be coupled with a system architecture and a security architecture that allow the 3GPP operators to retain control of the device behavior, for example who can emit discovery signals, when and where, what information do they carry, and what devices should do once they discover each other.”
Currently use cases and service requirements are discussed for the D2D communications under TGS-SA WG1. The following use cases have been proposed:
a) social applications, such as exchange of files, photos, text messages, etc., VoIP conversations, one-way streaming video and two-way video conference;
b) local advertising;
c) multiplayer gaming: for example, high resolution media (voice & video) can be exchanged interactively either with all participants or team members within a game environment, and the control inputs are expected to be received by all game participants with an ability to maintain causality;
d) network offloading: when an opportunistic proximity offload potential exists, Device 1 initiates a transfer of the media flow from the macro network to a proximity communications session with Device 2, conserving macro network resources while maintaining the quality of user experience for the media session;
e) smart meters: communication among low capability MTC devices, vehicular communication (safety and non-safety), and general M2M communication among different capability devices/machines in long term;
f) public safety: for example, TETRA like functionality. Furthermore, two types of D2D communication are of interest. One is the network controlled D2D communications taking place under coverage of the controlling network and the other is ad hoc D2D communications taking place without any cellular system coverage supporting the D2D communications. Moreover, radio resource allocation for the D2D discovery to allow devices belonging to multiple cells to discover each other in the network controlled D2D operation may be another challenge.